Organizations are a means to group databases, alerts, security rules, etc. into collections that mimic your real-world workgroups.
All access control in SecureCloudDB is performed by inspecting the members of an organization; each member of the organization has permission to read and modify all data owned by the organization, but not data owned by any other organizations.
A user may be a member of multiple organizations in order to interact with multiple different workgroups.
This allows for the use of powerful features such as employing an organization as a library of templates that can be copied to other organizations.